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Nectar robbers

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A year ago, after the bushfires, when everything that wasn’t burnt was scorched or looking like it had heat stroke, I planted a big pot of salvia for a quick burst of flowers for whatever insects had survived. It became a gathering point for native bees and honey bees alike, and every time I looked at it I felt I’d done something good. This summer it reflowered, and it continues to flower: an enormous coronet of ‘Hot Lips’ salvia with its circus flowers of pink and white; smaller, more compact, deep purple salvia beneath. Earlier this morning there was a dragonfly on its stalks, and just now two blue-banded bees (Amegilla cingulata), with their familiar buzz, careering around, dipping in and out. One is carrying a big yellow bundle of pollen on one of its back legs.

Not for the first time I wondered about nectar and pollen. Does the flower just keep exuding nectar, or does it run out? Why do the bees choose one flower over another? Why do they sometimes pop into one then pop out again immediately? And why are the blue-banded bees sometimes in the flower and sometimes under the flower, below the base of the petals?

Many hours later I have some answers. But first, I had to get some definitions.

Nectar.

Nectar is a sweet, nutritious secretion produced by a flower’s nectaries. It is mainly sugars (fructose, glucose and sucrose), but may contain traces of other elements, such as amino acids, salts and essential oils. Its composition varies enormously, depending on the plant species, soil and air conditions. Fascinatingly, the connection between a plant and its pollinator may be built in to the nectar:

All these substances often impart a particular taste and odour that may be essential for maintaining certain pollinator groups.[1]

Nectar is secreted from the nectaries in a distinctive pattern for each species, maybe in response to or just in tune with the different pollinators’ needs. The sugar levels may change as nectar is taken, or not. One study of nectar production in salvia showed varying levels of nectar production through the day, depending on the type of salvia, with average production ranging from lows of less than 0.5 µl to highs of 1.75 µl per flower between 9 am and 2 pm. The researchers found that most of the flowers stopped producing nectar after 2 pm. Removal of nectar, either by the researchers or by bees, did not stop the flower from producing nectar.

Nectaries.

The position of the nectaries is not fixed within the flower.

To ensure that ideally only legitimate pollinators can access the reward (and in that way successfully transfer pollen), flowers are often “built” around the nectary or the nectar.[3]

However, nectaries are usually found at the base of the stamens, so the pollinator comes into contact with the pollen as it goes into the flower.

Pollen, and other parts of the flower.

At this point I had to go back to flower terminology. Pollen grains contain the male gametes of plants. They are found on the anther, which is at the top of the stamen. When pollen is transferred to the stigma, it (hopefully) germinates. A pollen tube grows from the stigma down the style to fuse with the female nucleus in the ovary. The style and stamen are those fine upright parts of a flower, typically visible in the middle of the petals. So the importance of attracting pollinators lies in the fact that pollen may be being produced in one flower at a time when its stigmas are not receptive. The pollen carried by the pollinator to another plant’s flowers may find a more receptive stigma, leading to germination.

Putting it all together.

So nectar attracts bees (and other pollinators) in the hope that they will pick up some pollen and carry it around, leading to the survival of the species. Nectar is often exuded in small amounts to attract many different pollinators throughout the day, improving the chances of spreading the pollen around.

And those blue-banded bees sucking at the base of the flower?

Some insects, known generally as nectar robbers, bypass the sexual organs of the flowers to obtain nectar, often by penetrating the outside of the flower rather than entering it. In this way, nectar robbers ‘steal’ the nectar reward without facilitating pollination.[4]

Ooh. Nectar robbers!

[1] https://academic.oup.com/aob/article/94/2/269/174092

[2] http://sixseven.org/NectarMonitoring.pdf

[3] https://www.botany.one/2018/07/on-nectaries-and-floral-architecture/

[4] https://www.britannica.com/science/nectar

Fifty words for forty-nine days

22 Saturday Aug 2020

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22 August 2020

I caught the bush in suffragette colours yesterday. Newly green trees, hardenbergia draping pointillist purple blooms over fences, shy unnameable bushes dotted in white and, in a low haze, the violet flowers of Patersonia, native iris, three triangular petals windmilling from the centre. Overnight they shrivelled, purple blobs on stems.

We can be lyrebirds

02 Sunday Feb 2020

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Yesterday was hot. Oven hot. Even as the sun went down it was hot. Last night was hot. I woke from my final bit of restless sleep and, thirsty, reached for my cup of water. The water had become tepid overnight.

Today will also be hot. I sit in the shade with my breakfast and enjoy the light breeze – cool, disarming – while I can, before I’m forced into the house, blinds drawn, seeking out any habitable corner.

The bush is quiet. A small flock of birds flies overhead, quietly. Are they in mourning in this heat-scorched landscape? Lucky not to have burnt, large patches of trees are nevertheless covered in dead, brown leaves. I can almost see how the waves, the billows of heat came off the fire, landing in this patch, and this one.

A kookaburra calls. A deep throaty call. There is no reply. None of the hilarious groups of chuckling I was hearing a few months ago.

One of the good news bushfire stories I’ve read recently is about a group of lyrebirds sheltering in a dam while a fire raged around them. I’ve seen a photo, the lyrebirds in startled poses dotted awkwardly around the dam’s edge. The wonder is that they got there – fiercely territorial, they would have had to walk through each other’s territory to reach it – and the other wonder is that they stayed there, jostling, overcoming their innate competitiveness. Maybe ‘jostling’ is the wrong word. Maybe they were more like magnets with their same sides facing, only reaching a certain point of proximity before being repelled, maintaining a bare minimum gap. I look out at this silent bush around me and wonder if any unseen scenes of miraculous behaviour occurred around our muddy little dam. Last night, standing on the deck in the slightly cooler air, a sickly half-moon of cream-yellow above the trees, I heard a wallaby or kangaroo crunching through the leaves. I saw the quiet flight of an owl, felt a tiny bat shape its dive around my head. Did they all survive near the dam, each hunkered down in its own sweet way?

But I’m wary of these good news bushfire stories, these images of impossibly coloured leaves sprouting from thickly blackened trunks. Just as I’m wary of conversations that start with ‘We’ve always had fires’ or ‘This is how I remember summers in childhood.’ I’m wary of them being the beginning of a smoothing over, a covering up, a pretence of normality. A shrugging of the shoulders that accompanies a statement like, ‘Ah, nature! She’s a bastard.’ I want the agitation of emergency to endure. My little neck of the woods is safe for now but others aren’t. When Greta Thunberg says ‘Our house is burning’ she’s not talking about her family’s house, or her country’s house, she’s talking about the planet’s house. It seems to be human nature – and not an aspect of it that we can be proud of – to think small when we think of ‘our’, and to use ‘our’ as an exclusive force against ‘their’. The first – and maybe the hardest – step to take against climate change seems to be that we have to see ‘our’ in a different way. We have to quell the basic human desire to improve our lot at the expense of others, where ‘expense of others’ might mean exploiting others, ignoring others or using up the resources of others. If lyrebirds can challenge their instincts in order to survive, why can’t we?

Thank you firies

14 Tuesday Jan 2020

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When I turn off the highway I notice handmade signs dotted along the road. ‘Thank you firies’ they say. These are heartfelt messages. There are patches of burnt out bush and the ground is covered in leaf-litter from trees shedding their leaves to survive. Everything looks exhausted, drooping. The bush is quiet: few birds, nothing bigger. This is the land that the fire approached, having jumped the Shoalhaven River after days of sitting at its edge, slavering. You can see that the land itself couldn’t have resisted. You can see how the fire would have gobbled up that leaf-litter and bounced into the trees themselves, crawling up the trunks. How it would have leapt through the canopy, looking for more to devour.

The stories I hear from my neighbours are of miracles and lucky breaks. We’re lucky the firies chose this spot to try to draw a line against the mighty Currowan fire, so it didn’t spread down to the more inhabited parts of north Nowra. We’re lucky they contained it where they did, that a neighbour was here to show the firies from Queensland where the overgrown fire trails were. That a firebreak got out of hand but they firebombed it back into control. We’re lucky our houses didn’t explode like one neighbour’s friend. We’re lucky another neighbour has a son who’s a firie, who came up here to check on how it was going, sending back messages of reassurance.

We shake ourselves and say it again. We’re lucky that we didn’t join the hundreds of thousands, millions, of Australians disastrously affected by the bushfires that have been burning across the country since September. That we didn’t, along with so many others, lose our much-loved house. We had some days of worry, one night of complete resignation facing the worst. It is a holiday home, not our only house. And it is a house, not our lives, or our livelihoods. But it is our house. The house we’ve built over the last two years, and only lived in for the past year. Planned and furnished and filled with love. It’s the house Martin was taken from to the Shoalhaven hospital. It’s the house I returned to the same night, after a day of hospital staff stabilising Martin’s breathing, to find the whole community gathered nearby around the pizza oven. They flocked to me, invited me in, loaded me up with food and warmth. It’s the house and community I have planned to live in in years to come.

But even though the house is still standing and even the plants in the planter box have survived, something has gone. Through the missing trees I can see houses I never knew were there. I stand on the ashy ground and see burnt leaves everywhere. No insects bang at the night-time windows. More than that, it’s a sense of trust that has gone. The trust that fires can be controlled. That this little house would be here for me, that I would add to the garden and learn all the plants, all the birds in the bush around me. Having imagined the destruction of such a raging fire, I can’t unimagine it. It’s a version of the world that stays with me. In one moment, it all could have been lost. The fact that it wasn’t means I’m sitting in a ghost house, where ruins might have been. I can’t look at the bush or be in the house without that knowledge. It all looks transient now, shaky, the lines blurring in and out of view, dream-like.

 

My September challenge

28 Saturday Sep 2019

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A couple of weeks ago I decided to set myself a challenge: to do something personal about climate change each month. My challenge for September was to find out which was the least damaging petrol for the environment. Spending time in the bush at Tapitallee is a wonderful antidote to the pressures of city living, but driving down here is an environmental burden.

It turned out there was no simple answer to my question. And the answers I found were dispiriting – more evidence of woeful environmental leadership in Australia. The articles on the subject were unanimous – ‘compared with most of the rest of the world, our fuel is filthy’[1]  and ‘… this country still uses much dirtier fuel than most of the rest of the world. Indeed, Australia is ranked 70th in terms of fuel quality because of the relatively high percentage of sulphur permitted.’[2]  and ‘Australia’s 91-octane standard fuel is allowed to have sulphur levels as high as 150 parts per million. The world standard in markets such as China, Europe, India and Japan is 10 ppm.’[3]

The levels of sulphur in our petrol are a problem because our petrol is ‘pumping significantly more sulphur dioxide – a common cause of breathing problems and generator of acid rain – into the atmosphere than other OECD members, creating excessive engine wear for consumers and even costing us more at the pump, because the dirty fuel doesn’t burn as efficiently as if it had less sulphur.’[4] Moreover, because our petrol has these high levels of sulphur, ‘the latest-technology, low-emission engines cannot be supported in the domestic market. “If you go to a higher quality fuel, the vast majority of vehicles on our roads automatically (become) more fuel efficient,” said Mr Weber [chief executive of the Federal Chamber of Automotive Industries (FCAI)]. “There would be an improvement in the fuel economy of vehicles across the fleet of 17 million vehicles in Australia, not just the new ones”.’[5] The FCAI has said that ‘improving Australia’s fuel quality would offer a “3% to 5%” improvement on CO2 performance “overnight”.’[6]

We have four types of petrol available: 91RON, 95RON, 98RON and E10. (RON means Research Octane Number – ‘Octane is the measure of a fuel’s ability to resist the phenomenon known as ‘knocking’ … [which] is the uncontrolled combustion of fuel that can destroy engine internals.’[7]) 91RON petrol has a 150 ppm sulphur content, while 95RON and 98RON have a 50 ppm sulphur content. So even our best petrol has five times more sulphur than the world standard.

E10 is not the obvious choice either. ‘E10 is a blend of regular unleaded (RON 91) petrol and between 9% and 10% ethanol. Blending the ethanol at this ratio increases the RON to 94.’[8] So E10 has 90% of the sulphur of 91RON petrol (so, 135 ppm). The manufacture of the ethanol is probably less environmentally detrimental than the production of petrol, and ethanol ‘is a clean burning fuel that produces less greenhouse gases than unleaded petrol’[9]. However, ‘the sustainability certification of Australian produced ethanol is not transparent. We know from studies conducted by organisations including the European Commission that when coal is used to produce ethanol, it can result in “little or no greenhouse gas emissions saving for ethanol compared to gasoline” on a well-to-wheel basis. This is a significant consideration for Australia, given our current reliance on fossil fuels.’[10] Also, ‘E10 has around 3% less energy than the equivalent amount of RON 91 petrol. On average, this can translate to an increase in fuel consumption of around 3%, which has about the same effect on fuel consumption as driving on tyres with inadequate air pressure.’[11]

So what, I hear you clamour, is our government doing about this? High levels of sulphur polluting our air and choking our people; dirty fuel leaving us unable to use the latest technology of low-emissions vehicles; unclear certification on ethanol – surely they’re keen to listen to the Federal Chamber of Automotive Industries and improve our CO2 performance ‘overnight’?

Well, in December 2016 the Department of the Environment and Energy released a discussion paper called ‘Better fuel for cleaner air’ which set out the problem succinctly:

  • Motor vehicle emissions can be split into two categories: noxious emissions which affect human health and the environment and contribute to respiratory illness, cardiovascular diseases and cancer, and greenhouse gas emissions which contribute to climate change.
  • Petrol fuelled light vehicle emissions are one of the major causes of air pollution in urban Australia. Our expanding vehicle feet, increasing urbanisation and aging population mean that further action is needed to improve air quality and reduce the health impacts of air pollution.
  • Improving fuel quality can help reduce the level of noxious emissions, which improves air quality and health outcomes.
  • Some advanced vehicle technologies (including advanced emissions control systems and certain fuel efficient engine technologies) require higher quality fuel to work effectively. The quality of fuel influences which engine and emission control technologies can be supplied to the Australian market.

It also states that ‘Catalytic converters in vehicles are designed to filter emissions and reduce noxious substances emitted from vehicles. Sulfur clogs the catalytic converters making them less effective.’ It then outlines five alternative approaches, ranging from ‘no change’ through to the staged introduction of world standards from 2020. Sadly, the decision that was reached was closer to the ‘no change’ than introducing the world standards[12]. The sulphur in petrol will be reduced to 10 ppm – from July 1 2027. The aromatic content in petrol will be reduced from 42 per cent to 35 per cent, effective 1 January 2022, to be reviewed and reduced by 2027. [‘Aromatic content’ refers to chemicals like benzene, toluene and xylene used to increase the petrol’s octane rating since lead was banned. The effect of these chemicals is being increasingly questioned. ‘The chemicals get released into the air as nano-sized particles – ultrafine particulate matter, or UFPs – that can be absorbed through the lungs or skin. Studies in peer-reviewed journals like the Journal of Environmental Science and Health, Environmental Health Perspectives and Particle and Environmental Toxicology, have linked these particles from aromatics to diseases ranging from ADHD to asthma.’[13]]

So where does that leave us? I’m thinking that E10 is only 10% ethanol, has 135 ppm sulphur, is less efficient, and even the production of the ethanol is not necessarily clean. So for now I’m opting for the petrols with less sulfur (RON95 and RON98). But I’m also looking into carbon offsets, and electric cars. My October challenge.

 

 

 

 

 

[1] https://www.whichcar.com.au/features/australias-petrol-is-one-of-the-dirtiest-in-the-world

[2] https://www.afr.com/opinion/cleaner-petrol-a-bigger-help-than-electric-cars-20180124-h0nnfg

[3] https://www.canberratimes.com.au/story/6079636/our-poor-quality-petrol-slows-the-drive-to-improved-emissions/

[4] https://www.whichcar.com.au/features/australias-petrol-is-one-of-the-dirtiest-in-the-world

[5] https://www.caradvice.com.au/714921/why-australia-needs-better-quality-fuel/

[6] https://www.theguardian.com/australia-news/2019/sep/02/eu-to-push-australia-to-clean-up-petrol-standards-as-part-of-free-trade-deal

[7] https://www.mynrma.com.au/membership/my-nrma-app/fuel-resources/can-premium-fuels-clean-your-engine

[8] https://www.e10fuelforthought.nsw.gov.au/facts

[9] https://www.racq.com.au/cars-and-driving/cars/owning-and-maintaining-a-car/facts-about-fuels/ethanol

[10] https://www.abc.net.au/news/2018-07-04/e10-cheapest-petrol-fuel-emissions-biofuels-ethanol-australia/9922938

[11] https://www.e10fuelforthought.nsw.gov.au/facts

[12] https://www.environment.gov.au/protection/fuel-quality/standards

[13] https://morningconsult.com/2015/04/22/growing-chorus-of-complaints-on-chemicals-in-gasoline/